A fly is standing on a boulder, which is rolling down a hill. The forward torque the fly exerts on the boulder when it has rolled $x$ meters, in newton meters, is given by $ \tau(x) = \dfrac{2}{1000}\sin\left(\dfrac{2\pi (x+0.2)}{4}\right)$. What is the midline of this function? Give an exact answer. $y = $
The midline of a function is the function that cuts halfway between its minimum and maximum values. The maximum and minimum values occur when $\sin\left(\dfrac{2\pi (x+0.2)}{4}\right) = \pm 1$, when $\tau(x) = \pm \dfrac{2}{1000}$. So the midline is halfway between $\dfrac{2}{1000}$ and $-\dfrac{2}{1000}$. The midline of this function is the line $y = 0$.